The development of visual experience
Vision and visual cognition is experience-dependent with likely multiple sensitive periods, but we know very little about statistics of visual experience at the scale of everyday life and how they might change with development. By traditional assumptions, the world at the massive scale of daily life presents pretty much the same visual statistics to all perceivers. I will present an overview our work on ego-centric vision showing that this is not the case. The momentary image received at the eye is spatially selective, dependent on the location, posture and behavior of the perceiver. If a perceiver’s location, possible postures and/or preferences for looking at some kinds of scenes over others are constrained, then their sampling of images from the world and thus the visual statistics at the scale of daily life could be biased. I will present evidence with respect to both low-level and higher level visual statistics about the developmental changes in the visual input over the first 18 months post-birth.
Circuit solutions for programming actions
The hippocampus is one of the few regions in the adult mammalian brain which is endowed with life-long neurogenesis. Despite intense investigation, it remains unclear how neurons newly-generated may retain unique functions that contribute to modulate hippocampal information processing and cognition. In this talk, I will present some recent findings revealing how enhanced forms of plasticity in adult-born neurons underlie the way they become incorporated into pre-existing networks in response to experience.
Restructuring cortical feedback circuits
We hardly notice when there is a speck on our glasses, the obstructed visual information seems to be magically filled in. The mechanistic basis for this fundamental perceptual phenomenon has, however, remained obscure. What enables neurons in the visual system to respond to context when the stimulus is not available? While feedforward information drives the activity in cortex, feedback information is thought to provide contextual signals that are merely modulatory. We have made the discovery that mouse primary visual cortical neurons are strongly driven by feedback projections from higher visual areas when their feedforward sensory input from the retina is missing. This drive is so strong that it makes visual cortical neurons fire as much as if they were receiving a direct sensory input. These signals are likely used to predict input from the feedforward pathway. Preliminary results show that these feedback projections are strongly influenced by experience and learning.
Students to Professors: Inspiring NeurotechEU Women
The NeurotechEU student councils invites you to a special event on the occasion of the International Women's Day. 15 different speakers from very different backgrounds, seniority and expertise will share their experience on women in science, from students, to professeurs, to researchers, to the European Commission, discover their very unique insights.
Ways to think about the brain
Historically, research on the brain has been working its way in from the outside world, hoping that such systematic exploration will take us some day to the middle and on through the middle to the output. Ever since the time of Aristotle, philosophers and scientists have assumed that the brain (or, more precisely, the mind) is initially a blank slate filled up gradually with experience in an outside-in manner. An alternative, brain-centric view, the one I am promoting, is that self-organized brain networks induce a vast repertoire of preformed neuronal patterns. While interacting with the world, some of these initially ‘nonsensical’ patterns acquire behavioral significance or meaning. Thus, experience is primarily a process of matching preexisting neuronal dynamics to events in the world. I suggest that perpetually active, internal dynamic is the source of cognition, a neuronal operation disengaged from immediate senses.
How Memory Guides Value-Based Decisions
From robots to humans, the ability to learn from experience turns a rigid response system into a flexible, adaptive one. In this talk, I will discuss emerging findings regarding the neural and cognitive mechanisms by which learning shapes decisions. The lecture will focus on how multiple brain regions interact to support learning, what this means for how memories are built, and the consequences for how decisions are made. Results emerging from this work challenge the traditional view of separate learning systems and advance understanding of how memory biases decisions in both adaptive and maladaptive ways.
How development sculpts memory circuits
In mammals, the selective transformation of transient experience into stored memory occurs in the hippocampus, which develops representations of specific events in the context in which they occur. In this talk, I will focus on the development of hippocampal circuits and the self-organized dynamics embedded in them since the latter critically support the role of the hippocampus in memory. I will discuss evidence that adult hippocampal cells and circuits are remarkably sculpted by development, as early as embryonic neurogenesis. We argue that these primary developmental programs provide a scaffold onto which later experience of the external world can be grafted. Next, I will present data on the emergence of recurrent connectivity and self-organized dynamics in hippocampal circuits and outline the critical turn points and discontinuities in that developmental journey.
Hippocampal replays appear after a single experience and slow down with subsequent experience as greater detail is incorporated
The hippocampus is implicated in memory formation, and neurons in the hippocampus take part in replay sequences, time-compressed reactivations of trajectories through space the animal has previously explored. These replay sequences have been proposed to be a form of memory for previously experienced places. I will present work exploring how these replays appear and change with experience. By recording from large ensembles of hippocampal neurons as rats explored novel and familiar linear tracks in various experiments, we found that hippocampal replays appear after a single experience and slow down with subsequent experience as greater detail is incorporated. We also investigated hover-and-jump dynamics within replays that are associated with the slow gamma (25-50Hz) oscillation in the LFP and found that replays slow down by adding more hover locations, corresponding to depiction of the behavioral trajectory with increased resolution. Thus, replays can reflect single experiences, and be rapidly modified by subsequent experience to incorporate more detail, consistent with their proposed role as a basic mechanism of hippocampally dependent memory.